The present invention relates to an indexable cutting insert for face milling cutters, and the like of the type including a cutter body having at least one cutting insert pocket positioned at a peripheral part thereof, and being adapted for axial rotation with respect to a work piece. The insert comprises an upper surface, a lower surface and generally perpendicularly connecting side surfaces, of which two adjacent side surfaces meet in a rounded corner defined by a radius R. A peripheral land connects to the side surfaces and forms a peripheral cutting edge. The land connects at least partly to a downwardly and inwardly sloping chip surface. The corner has a bisector.
Cutting inserts for face milling which are provided with corner chamfers are previously known. A drawback of these known inserts is that the active corner chamfer has a constant setting angle during the machining of the entire work piece. At machining of engine blocks of cast iron the constant setting angle results in that the cutting insert tears material away from the work piece instead of cutting it away and therefore the surface of the work piece becomes impaired, especially at its border edges and its cylinder borings. A drawback of conventional inserts which have a strengthening land of constant width is that in the active corner of the insert, where the largest cutting forces arise, the land becomes more worn than at a distance from the corner.
One object of the present invention is to provide an indexable cutting insert which makes a clean cut also at the periphery of the work piece.
Another object of the present invention is to provide a cutting insert having maximum length of life.
Still another object of the present invention is to provide a cutting insert which demands little power to cut.
Still another object of the present invention is to provide a cutting insert which in spite of a negative basic shape achieves a positive cutting geometry.